A current providing system, for providing an output current, which comprises: a frequency detecting circuit, for receiving at least one input signal, and for detecting a frequency of the input signal; a frequency-controlled current providing circuit, for providing the output current according to the input signal frequency when the input signal frequency is in a first predetermined range; and a predetermined current providing circuit, for providing the output current with a first predetermined current value, when the input signal frequency is not in the first predetermined range.
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